The invention is concerned with a door lock, in particular for motor vehicles, having a rotary latch and a closing aid which acts on the latter and, with the aid of a drive, carries along the door to be closed over the last section into the closed position.
In the case of door locks of this type, there is the problem that the closing aid together with its drive considerably increases the space requirement of the door lock and therefore the door lock can no longer be used universally for various installation purposes, but instead complicated adaptations to the spatial conditions present in each case have to be undertaken, if installation is possible at all.
The object of the invention is to provide a door lock having a closing aid which can be adapted more easily to the given spatial installation conditions.
According to the invention, the object is achieved by a door lock of the type described at the beginning, in which the drive of the closing aid is separated structurally from the door lock and a flexible drive element is provided for transmitting force from the drive to the rotary latch.
The coupling of the closing aid, which is driven, for example, by an electric motor, to the door lock with the aid of a flexible drive element permits the door lock itself to be designed compactly, so that it can be used without substantial changes for a multiplicity of application purposes, even under restricted spatial conditions. The drive of the closing aid can be fitted independently of the door lock at a point in the relatively close vicinity of the door lock, in which case the length of the flexible drive element has merely to be adapted to the installation location of the drive.
The door lock according to the invention is therefore suitable not only for use in new structures, but may in principle also be installed, for example, into the cavities of existing structures of vehicle doors.
A further advantage of the flexible drive element resides in force being transmitted in a virtually loss-free manner and in its very diet manner of operating.
In a preferred development of the invention, provision is made for the rotary latch to be moveable into its closed position counter to the force of a restoring spring 58 by the flexible drive element in the form of a tension element.
Since the rotary latch is restored with the aid of the restoring spring 56 as is customary in door locks, it is sufficient if the closing aid is effective only in one direction of movement, in which case the drive element can be wound. A solution for this type of closing aid manages with very few parts and offers high degree of functional reliability.
The flexible drive element is preferably designed as a metal cable which, with a small cross section, enables the necessary tensile forces to be transmitted and offers good reliability against breakdown. In principle, however, it is also conceivable to use tension ties, belts, chains or the like as the flexible drive element.
The flexible drive element preferably undergoes a change in direction with the aid of at least one deflection roller, A deflection roller Of this type firstly facilitates the adaptation to difficult installation positions and secondly, in a preferred development of the invention, in which the deflection roller can be moved from its normal position into an auxiliary opening position shortening the path of the drive element, an auxiliary release is readily possible, even when the closing aid is activated. The deflection roller can be mounted on the door lock, on the drive of the closing aid or, independently of both of these, on the door structure
If the deflection roller has an appropriate path of movement, the drive of the closing aid does not even have to be switched off, in which case the auxiliary release of course not only causes yielding by the deflection roller being pivoted away or inward, but at the same time causes release of the rotary latch which, under some circumstances, has already engaged in the preliminary catch or main catch.
In a particularly preferred embodiment of the invention, the moveability of the deflection roller into the auxiliary opening position is effected by the deflection roller being arranged on a toggle lever which can folded in by actuation of the auxiliary opening device. The advantage of a toggle lever structure resides in said toggle lever in the stretched state being virtually infinitely stiff, on the one hand, and thereby enabling the transmission even of high closing forces, and secondly, being moveable beyond a dead center position, by a comparatively small actuating force being exerted at the buckling point, after which the toggle lever immediately folds in, when a load is applied to the deflection roller, and ensures the necessary release of the drive element. A restoring spring 56 ensures that after an auxiliary triggering the toggle lever automatically returns back into its stretched position.
In order to ensure satisfactory functioning of the closing aid, it is expedient to keep the drive element under stress in all operating states by at least one prestressting spring. In this case, the prestressing spring has to be capable of keeping the drive element under a sufficient tensile stress even during an auxiliary release and corresponding shortening of the path of the drive element, in order, for example, to ensure that the flexible drive element cannot spring away from the deflection roller.
In the simplest case, the restoring spring of the rotary latch can ensure that the drive element is prestressed, but this preferably takes place by means of a restoring spring of a driving lever acting on the rotary latch. As an alternative, it is conceivable to provide the prestress with the aid of a resiliently mounted drive roller, a deflection roller acting in its normal position as a clamping roller or else with the aid of a drive element which can be extended in the longitudinal direction. Combinations of a number of these prestressing elements are likewise conceivable,